Flynn joined fellow hooker Andrew Hore as another front row casualty on the All Blacks end of year tour, after scans taken after the team arrived here from Ireland revealed his sore left arm was in fact fractured.
The 27-year-old sustained the latest blow to his injury-cursed career playing against Munster in Limerick on Tuesday night but the severity of the knock was not apparent until after the match.
Flynn was replaced in the 62nd minute, a tactical substitution for debutant Hikawera Elliot.
The former Canterbury captain was named on the bench when the All Blacks team to play Wales at the Millennium Stadium on Sunday morning was named yesterday but appeared disconsolate when the team landed in the Welsh capital.
He told medical staff he was concerned about pain in his left arm, and hours later an x-ray confirmed his fears.
Elliot joined the bench as back-up for Keven Mealamu -- who essentially starts his fourth test in succession.
A decision on whether Flynn will be replaced depends on how Mealamu and Elliot scrub up after the third leg of the All Blacks Grand Slam attempt.
Rather than call-in a replacement for the All Blacks tour finale against England at Twickenham next weekend they may, if necessary, revert to a tactic they had on stand-by in South Africa during this year's Tri-Nations.
Had Mealamu or Hore broken down, loosehead Tony Woodcock would throw to the lineout and another prop John Afoa would play at hooker.
Flynn's latest arm problem is yet another setback for the former Southlander, who finally found himself back in the All Blacks frame this season after four years on the outer.
Flynn made his debut at the 2003 World Cup but played the last of his three tests on the following year's northern hemisphere tour.
His development was then blocked by the emergence of Hore and Derren Witcombe while Anton Oliver and Mealamu were considered the senior hookers leading into the last World Cup.
Broken arms have stunted his career.
In 2002 he broke his left arm playing for Southland and broke it again playing for the Crusaders in 2003.
In May this year he fractured his right arm while playing in Super 14 semifinal against the Hurricanes.
Flynn had been one of the stand out hookers of that competition and he reproduced his form when belatedly joining Canterbury's successful Air NZ Cup campaign.
Hore's tour-ending ankle injury four minutes into the clash with Australia in Hong Kong on November 1 enabled Flynn to back-up Mealamu for the test wins over Scotland and Ireland.
Meanwhile, Mealamu will start his third successive test this weekend -- though he practically played all of the final Bledisloe Cup match as well.
The Aucklander had no concerns about his workload despite head coach Graham Henry often claiming elite players could not be expected to perform at optimum levels if they had to play more than three consecutive test matches.
"I'm feeling good, the tour's going really quick to be honest," Mealamu said.
"It's helped that it hasn't been as cold as we expected. Maybe the warmer weather and the fact we haven't really trained in the rain has made the tour go a lot quicker."
Mealamu expressed confidence in Elliot -- who joined the squad in Scotland as Hore's replacement -- after the New Zealand Maori hooker marked his All Blacks debut with an assured 18-minute stint against a fired-up Munster side.
"He did really well considering he came on in a pressure situation," Mealamu said.
"The wait has definitely been worth it for him."
